The quest for the cosmological parameters that describe our universe continues to motivate the scientific community to undertake very large survey initiatives across the electromagnetic spectrum. ...Over the past two decades, the Chandra and XMM-Newton observatories have supported numerous studies of X-ray-selected clusters of galaxies, active galactic nuclei (AGNs), and the X-ray background. The present paper is the first in a series reporting results of the XXL-XMM survey; it comes at a time when the Planck mission results are being finalized. Aims. We present the XXL Survey, the largest XMM programme totaling some 6.9 Ms to date and involving an international consortium of roughly 100 members. The XXL Survey covers two extragalactic areas of 25 deg2 each at a point-source sensitivity of approx. 5 x 10(exp 15) erg/s/sq cm in the 0.5-2 keV band (completeness limit). The surveys main goals are to provide constraints on the dark energy equation of state from the space-time-distribution of clusters of galaxies and to serve as a pathfinder for future, wide-area X-ray missions. We review science objectives, including cluster studies, AGN evolution, and large-scale structure, that are being conducted with the support of approximately 30 follow-up programs. Methods. We describe the 542 XMM observations along with the associated multi- and numerical simulation programmes. We give a detailed account of the X-ray processing steps and describe innovative tools being developed for the cosmological analysis. Results. The paper provides a thorough evaluation of the X-ray data, including quality controls, photon statistics, exposure and background maps, and sky coverage. Source catalogue construction and multi-associations are briefly described. This material will be the basis for the calculation of the cluster and AGN selection functions, critical elements of the cosmological and science analyses. Conclusions. The XXL multi- data set will have a unique lasting legacy value for cosmological and extragalactic studies and will serve asa calibration resource for future dark energy studies with clusters and other X-ray selected sources. With the present article, we release the XMM XXL photon and smoothed images along with the corresponding exposure maps.
The XXL Survey Adami, C.; Giles, P.; Koulouridis, E. ...
Astronomy and astrophysics (Berlin),
12/2018, Letnik:
620
Journal Article
Recenzirano
Odprti dostop
Context.
In the currently debated context of using clusters of galaxies as cosmological probes, the need for well-defined cluster samples is critical.
Aims.
The XXL Survey has been specifically ...designed to provide a well characterised sample of some 500 X-ray detected clusters suitable for cosmological studies. The main goal of present article is to make public and describe the properties of the cluster catalogue in its present state, as well as of associated catalogues of more specific objects such as super-clusters and fossil groups.
Methods.
Following from the publication of the hundred brightest XXL clusters, we now release a sample containing 365 clusters in total, down to a flux of a few 10
−15
erg s
−1
cm
−2
in the 0.5–2 keV band and in a 1′ aperture. This release contains the complete subset of clusters for which the selection function is well determined plus all X-ray clusters which are, to date, spectroscopically confirmed. In this paper, we give the details of the follow-up observations and explain the procedure adopted to validate the cluster spectroscopic redshifts. Considering the whole XXL cluster sample, we have provided two types of selection, both complete in a particular sense: one based on flux-morphology criteria, and an alternative based on the 0.5–2 keV flux within 1 arcmin of the cluster centre. We have also provided X-ray temperature measurements for 80% of the clusters having a flux larger than 9 × 10
−15
erg s
−1
cm
−2
.
Results.
Our cluster sample extends from
z
~ 0 to
z
~ 1.2, with one cluster at
z
~ 2. Clusters were identified through a mean number of six spectroscopically confirmed cluster members. The largest number of confirmed spectroscopic members in a cluster is 41. Our updated luminosity function and luminosity–temperature relation are compatible with our previous determinations based on the 100 brightest clusters, but show smaller uncertainties. We also present an enlarged list of super-clusters and a sample of 18 possible fossil groups.
Conclusions.
This intermediate publication is the last before the final release of the complete XXL cluster catalogue when the ongoing C2 cluster spectroscopic follow-up is complete. It provides a unique inventory of medium-mass clusters over a 50 deg
2
area out to
z
~ 1.
This paper describes the observations and the first data release (DR1) of the ESO public spectroscopic survey “VANDELS, a deep VIMOS survey of the CANDELS CDFS and UDS fields”. The main targets of ...VANDELS are star-forming galaxies at redshift 2.4 < z < 5.5, an epoch when the Universe had not yet reached 20% of its current age, and massive passive galaxies in the range 1 < z < 2.5. By adopting a strategy of ultra-long exposure times, ranging from a minimum of 20 h to a maximum of 80 h per source, VANDELS is specifically designed to be the deepest-ever spectroscopic survey of the high-redshift Universe. Exploiting the red sensitivity of the refurbished VIMOS spectrograph, the survey is obtaining ultra-deep optical spectroscopy covering the wavelength range 4800–10 000 Å with a sufficiently high signal-to-noise ratio to investigate the astrophysics of high-redshift galaxy evolution via detailed absorption line studies of well-defined samples of high-redshift galaxies. VANDELS-DR1 is the release of all medium-resolution spectroscopic data obtained during the first season of observations, on a 0.2 square degree area centered around the CANDELS-CDFS (Chandra deep-field south) and CANDELS-UDS (ultra-deep survey) areas. It includes data for all galaxies for which the total (or half of the total) scheduled integration time was completed. The DR1 contains 879 individual objects, approximately half in each of the two fields, that have a measured redshift, with the highest reliable redshifts reaching zspec ~ 6. In DR1 we include fully wavelength-calibrated and flux-calibrated 1D spectra, the associated error spectrum and sky spectrum, and the associated wavelength-calibrated 2D spectra. We also provide a catalog with the essential galaxy parameters, including spectroscopic redshifts and redshift quality flags measured by the collaboration. We present the survey layout and observations, the data reduction and redshift measurement procedure, and the general properties of the VANDELS-DR1 sample. In particular, we discuss the spectroscopic redshift distribution and the accuracy of the photometricredshifts for each individual target category, and we provide some examples of data products for the various target typesand the different quality flags. All VANDELS-DR1 data are publicly available and can be retrieved from the ESO archive. Two further data releases are foreseen in the next two years, and a final data release is currently scheduled for June 2020, which will include an improved rereduction of the entire spectroscopic data set.
Context.
We present radial-velocity measurements of eight stars observed with the HARPS Echelle spectrograph mounted on the 3.6-m telescope in La Silla (ESO, Chile). Data span more than ten years and ...highlight the long-term stability of the instrument.
Aims.
We search for potential planets orbiting HD 20003, HD 20781, HD 21693, HD 31527, HD 45184, HD 51608, HD 134060 and HD 136352 to increase the number of known planetary systems and thus better constrain exoplanet statistics.
Methods.
After a preliminary phase looking for signals using generalized Lomb-Scargle periodograms, we perform a careful analysis of all signals to separate bona-fide planets from signals induced by stellar activity and instrumental systematics. We finally secure the detection of all planets using the efficient MCMC available on the Data and Analysis Center for Exoplanets (DACE web-platform), using model comparison whenever necessary.
Results.
In total, we report the detection of twenty new super-Earth to Neptune-mass planets, with minimum masses ranging from 2 to 30
M
Earth
and periods ranging from 3 to 1300 days, in multiple systems with two to four planets. Adding CORALIE and HARPS measurements of HD20782 to the already published data, we also improve the characterization of the extremely eccentric Jupiter orbiting this visual companion of HD 20781.
VANDELS is an ESO Public Spectroscopic Survey designed to build a sample of high-signal-to-noise ratio, medium-resolution spectra of galaxies at redshifts between 1 and 6.5. Here we present the final ...Public Data Release of the VANDELS Survey, comprising 2087 redshift measurements. We provide a detailed description of sample selection, observations, and data reduction procedures. The final catalogue reaches a target selection completeness of 40% at
i
AB
= 25. The high signal-to-noise ratio of the spectra (above 7 in 80% of the spectra) and the dispersion of 2.5 Å allowed us to measure redshifts with high precision, the redshift measurement success rate reaching almost 100%. Together with the redshift catalogue and the reduced spectra, we also provide optical mid-infrared photometry and physical parameters derived through fitting the spectral energy distribution. The observed galaxy sample comprises both passive and star forming galaxies covering a stellar mass range of 8.3 < Log(
M
*
/
M
⊙
) < 11.7.
The XXL Survey Pacaud, F; Clerc, N; Giles, P A ...
Astronomy and astrophysics (Berlin),
08/2016, Letnik:
592
Journal Article
Recenzirano
Odprti dostop
Context. The XXL Survey is the largest survey carried out by the XMM-Newton satellite and covers a total area of 50 square degrees distributed over two fields. It primarily aims at investigating the ...large-scale structures of the Universe using the distribution of galaxy clusters and active galactic nuclei as tracers of the matter distribution. The survey will ultimately uncover several hundreds of galaxy clusters out to a redshift of ~2 at a sensitivity of ~10 super(-14) ergs super(-1)cm super(-2) in the 0.5-2 keV band. Aims. This article presents the XXL bright cluster sample, a subsample of 100 galaxy clusters selected from the full XXL catalogue by setting a lower limit of 3 x 10 super(-14) erg s super(-1) cm super(-2) on the source flux within a 1? aperture. Methods. The selection function was estimated using a mixture of Monte Carlo simulations and analytical recipes that closely reproduce the source selection process. An extensive spectroscopic follow-up provided redshifts for 97 of the 100 clusters. We derived accurate X-ray parameters for all the sources. Scaling relations were self-consistently derived from the same sample in other publications of the series. On this basis, we study the number density, luminosity function, and spatial distribution of the sample. Results. The bright cluster sample consists of systems with masses between M sub(500)= 7 x 10 super(13) and 3 x 10 super(14)M sub(?), mostly located between z= 0.1 and 0.5. The observed sky density of clusters is slightly below the predictions from the WMAP9 model, and significantly below the prediction from the Planck 2015 cosmology. In general, within the current uncertainties of the cluster mass calibration, models with higher values of sigma sub(8) and/or Omega sub(M) appear more difficult to accommodate. We provide tight constraints on the cluster differential luminosity function and find no hint of evolution out to z~ 1. We also find strong evidence for the presence of large-scale structures in the XXL bright cluster sample and identify five new superclusters.
We present optical V and i-band light curves of the gravitationally lensed BAL quasar HE 2149-2745. The data, obtained with the 1.5 m Danish Telescope (ESO-La Silla) between October 1998 and December ...2000, are the first from a long-term project aimed at monitoring selected lensed quasars in the Southern Hemisphere. A time delay of $103\pm12$ days is determined from the light curves. In addition, VLT/FORS1 spectra of HE 2149-2745 are deconvolved in order to obtain the spectrum of the faint lensing galaxy, free of any contamination by the bright nearby two quasar images. By cross-correlating the spectrum with galaxy-templates we obtain a tentative redshift estimate of $z=0.495\pm0.01$. Adopting this redshift, a $\Omega=0.3$, $\Lambda=0.7$ cosmology, and a chosen analytical lens model, our time-delay measurement yields a Hubble constant of $H_{0}=66 \pm 8\, {\rm km}~{\rm s^{-1}}~{\rm Mpc^{-1}}$ (1σ error) with an estimated systematic error of $\pm3\, {\rm km}~{\rm s^{-1}}~{\rm Mpc^{-1}}$. Using non-parametric models yields $H_{0}=65 \pm 8\, {\rm km}~{\rm s^{-1}}~{\rm Mpc^{-1}}$ (1σ error) and confirms that the lens exhibits a very dense/concentrated mass profile. Finally, we note, as in other cases, that the flux ratio between the two quasar components is wavelength dependent. While the flux ratio in the broad emission lines – equal to 3.7 – remains constant with wavelength, the continuum of the brighter component is bluer. Although the data do not rule out extinction of one quasar image relative to the other as a possible explanation, the effect could also be produced by differential microlensing by stars in the lensing galaxy.
The XXL Survey Pacaud, F.; Pierre, M.; Melin, J.-B. ...
Astronomy and astrophysics (Berlin),
12/2018, Letnik:
620
Journal Article
Recenzirano
Odprti dostop
Context.
We present an estimation of cosmological parameters with clusters of galaxies.
Aims.
We constrain the Ω
m
,
σ
8
, and
w
parameters from a stand-alone sample of X-ray clusters detected in the ...50 deg
2
XMM-XXL survey with a well-defined selection function.
Methods.
We analyse the redshift distribution of a sample comprising 178 high signal-to-noise ratio clusters out to a redshift of unity. The cluster sample scaling relations are determined in a self-consistent manner.
Results.
In a lambda cold dark matter (ΛCDM) model, the cosmology favoured by the XXL clusters compares well with results derived from the
Planck
Sunyaev-Zel’dovich clusters for a totally different sample (mass/redshift range, selection biases, and scaling relations). However, with this preliminary sample and current mass calibration uncertainty, we find no inconsistency with the
Planck
CMB cosmology. If we relax the
w
parameter, the
Planck
CMB uncertainties increase by a factor of ~10 and become comparable with those from XXL clusters. Combining the two probes allows us to put constraints on Ω
m
= 0.316 ± 0.060,
σ
8
= 0.814 ± 0.054, and
w
= −1.02 ± 0.20.
Conclusions.
This first self-consistent cosmological analysis of a sample of serendipitous XMM clusters already provides interesting insights into the constraining power of the XXL survey. Subsequent analysis will use a larger sample extending to lower confidence detections and include additional observable information, potentially improving posterior uncertainties by roughly a factor of 3.
On 4 July 2005 at 05:52 UT, the impactor of NASA's Deep Impact (DI) mission crashed into comet 9P/Tempel 1 with a velocity of about 10 ${\rm km\,s}^{-1}$. The material ejected by the impact expanded ...into the normal coma, produced by ordinary cometary activity. The La Silla and Paranal sites of the European Southern Observatory (ESO) in Chile participated in the world-wide campaign to observe this event.
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